Is this a good place for bug reports? Or should I post this somewhere else?
Here are the steps for reproducing this bug on Mathematica 6.0.1.0 on Win32:
1. Start Mathematica and create a new notebook.
2. Type "Hello" (or any text) into the first cell of the notebook.
3. Select the cell (using Ctrl-A, Edit -> Select All, or some other method).
4. Convert it to a text-styled cell by using Alt-7, or Format -> Style
-> Text.
5. Click in the cell to put the cursor there, so you can type more input.
6. Create an inline cell by using Ctrl-9 or Insert -> Typesetting ->
Start Inline Cell. The cursor should be within the inline cell now.
7. Convert the cell to InputForm by using Ctrl-Shift-I or Cell ->
Convert To -> InputForm.
At this point, on my machine, Mathematica crashes and loses all my work.